Communication method and device

ABSTRACT

A communication method and device are applicable in a mobile communication system of LTE Type2 wideband TDD. The method includes transmitting, by a first communication device, to a second communication device a radio frame, where each half-frame of the radio frame including a data timeslot for transmitting data, an uplink special timeslot and a Downlink special timeslot for carrying synchronizing information, and the data timeslot is shorter than an original data timeslot by a first timeslot and/or the uplink special timeslot is shorter than an original uplink special timeslot by a second timeslot; and a part of the first timeslot or the second timeslot or the combination of the first timeslot and the second timeslot, having the length of one orthogonal frequency division multiplex symbol, carries a secondary synchronous channel.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a U.S. national stage filing of InternationalApplication No. PCT/CN2008/001672, filed Sep. 27, 2008, claimingpriority from Chinese Application No. 200710175463.1, filed Sep. 29,2007, which are both incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates to communication technologies andparticularly to a communication method and device.

BACKGROUND OF THE INVENTION

As illustrated in FIG. 1, a radio frame transmitted between a UserEquipment and a base station in a mobile communication system of LongTerm Evolution Type 2 wideband Time Division Duplex (LTE Type 2 TDD) hasa length of 10 ms. Each radio frame is divided into two half-frames.Each half-frame includes seven sub-frames (also referred to as datatimeslots) and three special timeslots. In an LTE system with abandwidth of 20 MHz, for example, the bandwidth of the system is 20 MHz,an interval between sub-carriers is Δf=15 KHz, the number of FFT samplepoints is NFFT=2048, and the minimum time unitTs=1/(Δf×NFFT)=1/(15000×2048)=0.03255 μs. In this case, each of theseven data timeslots is used for transmission of uplink or downlink dataand is consisted of Cyclic Prefixes (CPs) and Orthogonal FrequencyDivision Multiplex (OFDM) symbols, where each OFDM symbol has a lengthof 2048×Ts, each short CP has a length of 256×Ts, each long CP has alength of 544×Ts, and each data timeslot has a total length of 675 μs(20736×Ts). The data timeslots may be divided into uplink timeslots anddownlink timeslots; each downlink timeslot includes nine OFDM symbols inthe case of short CPs, or eight OFDM symbols in the case of long CPs,and each uplink timeslot includes nine long blocks in the case of shortCPs, or eight long blocks in the case of long CPs. The seven datatimeslots may be identified with #0, #1, #2, #3, #4, #5 and #6 or withTS0, TS1, TS2, TS3, TS4, TS5 and TS6, where #0 corresponds to TS0, #1corresponds to TS1, and the like. Timeslot #0 is used only for downlink.The three special timeslots include a downlink special timeslot (DwPTS),a guard timeslot (GP) and an uplink special timeslot (UpPTS), where thedownlink special timeslot DwPTS with a length of 2572×Ts is locatedsucceeding the timeslot TS0 and includes one CP (with a length of524×Ts) and one OFDM symbol (with a length of 2048×Ts), which is usedfor carrying a primary synchronous channel (P-SCH) to implementoperations such as searching for a cell and downlink synchronization,while a secondary synchronous channel (S-SCH) is transmitted in the lastsymbol of the data timeslot #0; the uplink special timeslot UpPTS with alength of 4340×Ts is located succeeding the GP and preceding thetimeslot TS1 to enable an uplink random access, etc; and the guardtimeslot GP with a length of 50 μs (1536×Ts), which carries no datasignal, is located preceding the uplink special timeslot UpPTS toprevent interference of the downlink special timeslot with the uplinkspecial timeslot.

In the foregoing data frame structure, occupancy of the last symbol ofthe timeslot #0 by the S-SCH limits the efficiency of transmittinginformation such as a broadcast channel (BCH) in the timeslot #0. On theother hand, since the DwPTS is spaced from the uplink timeslot by atimeslot GP only, when the DwPTS is drifting or the power of the DwPTSis increased, interference of the DwPTS with the uplink timeslot may becaused, resulting in a degraded communication quality.

SUMMARY OF THE INVENTION

Embodiments of the invention provide a communication method and deviceto address the problem of the limited efficiency of transmittinginformation such as the BCH in the timeslot #0.

An embodiment of the invention provides a communication methodapplicable in a mobile communication system of Long Term Evolution Type2 wideband Time Division Duplex, and the method includes:

transmitting, by a first communication device, to a second communicationdevice a radio frame, where each half-frame of the radio frame includesa data timeslot for transmitting data, an uplink special timeslot and adownlink special timeslot for carrying synchronization information;where the data timeslot is shorter than an original data timeslot by afirst timeslot and/or the uplink special timeslot is shorter than anoriginal uplink special timeslot by a second timeslot; and a part of thefirst timeslot or the second timeslot or the combination of the firsttimeslot and the second timeslot, having the length of one orthogonalfrequency division multiplex symbol, carries a secondary synchronouschannel.

Preferably, the part carrying the secondary synchronous channel isincluded in the downlink special timeslot, and is located at the head ofthe downlink special timeslot. Preferably, the downlink special timeslotis arranged at the head of the half-frame.

Preferably, at least part of the first timeslot and/or at least part ofthe second timeslot is located at the tail of the downlink specialtimeslot.

Preferably, the half-frame of the radio frame further includes a guardtimeslot for preventing interference between uplink and downlinktimeslots; and at least part of the first timeslot and/or at least partof the second timeslot is located in the guard timeslot.

An embodiment of the invention further provides a communication deviceapplicable in a mobile communication system of Long Term Evolution Type2 wideband Time Division Duplex, which includes:

a transmission unit, configured to transmit a radio frame, eachhalf-frame of the radio frame including a data timeslot for transmittingdata, an uplink special timeslot and a downlink special timeslot forcarrying synchronization information, where the data timeslot is shorterthan an original data timeslot by a first timeslot and/or the uplinkspecial timeslot is shorter than an original uplink special timeslot bya second timeslot; and a part of the first timeslot or the secondtimeslot or the combination of the first timeslot and the secondtimeslot, having the length of one orthogonal frequency divisionmultiplex symbol, carries a secondary synchronous channel.

Preferably, the part carrying the secondary synchronous channel isincluded in the downlink special timeslot, and is located at the head ofthe downlink special timeslot. Preferably, the downlink special timeslotis arranged at the head of the half-frame.

Preferably, at least part of the first timeslot and/or at least part ofthe second timeslot is located at the tail of the downlink specialtimeslot.

Preferably, the half-frame of the radio frame further includes a guardtimeslot for preventing interference between uplink and downlinktimeslots; and at least part of the first timeslot and/or at least partof the second timeslot is located in the guard timeslot.

According to the embodiments of the invention, through shortening inlength the data timeslot and/or the uplink special timeslot and makingreasonable use of the spared timeslot part due to the shortening of thedata timeslot and/or the uplink special timeslot, for example, byarranging that part in the GP, it is possible to increase an intervalbetween the DwPTS and the UpPTS to thereby reduce interference of theDwPTS with the uplink timeslot. Alternatively, by composing that sparedtimeslot part due to the shortening of the data timeslot and/or theuplink special timeslot into a symbol (referred to as a first symbol forthe sake of convenient descriptions) so as to add the symbol into thehalf-frame, it is possible to arrange the S-SCH in the first symbol tothereby avoid a symbol of any data timeslot from being occupied by theS-SCH, so that on one hand a utilization ratio of resources may beimproved, and on the other hand the timeslot of DwPTS may be moved, forexample, by arranging the DwPTS at the head of the half-frame, due totwo OFDM symbols being contained in the DwPTS to carry the S-SCH and theP-SCH, to thereby address effectively the problem of the interference ofthe DwPTS with the uplink timeslot due to an power increase of theDwPTS.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a schematic diagram of the structure of a radio framein the prior art;

FIG. 2 illustrates a schematic diagram of the structure of a radio frameaccording to a first embodiment of the invention;

FIG. 3 illustrates a schematic diagram of another structure of a radioframe according to a first embodiment of the invention; and

FIG. 4 illustrates a schematic diagram of a further structure of a radioframe according to a first embodiment of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The embodiments of the invention are described hereinafter withreference to the drawings for better understanding and implementing ofthe invention by those ordinarily skilled in the art.

A First Embodiment

An embodiment of the invention provides a communication methodincluding: transmitting, by a first communication device, a data frameto a second communication device. The data frame includes a datatimeslot, an uplink special timeslot, a downlink special timeslot and aguard timeslot, where the data timeslot and the uplink special timeslotare shorter than the respective existing timeslots, the downlink specialtimeslot and/or the guard timeslot are/is longer than the respectiveexisting timeslot(s), and a total length of the data timeslot, theuplink special timeslot, the downlink special timeslot and the guardtimeslot is kept unchanged. Particularly, the data timeslot is used fortransmission of uplink or downlink data; the downlink special timeslotis used for carrying synchronization information to implement operationsof searching for a cell, downlink synchronization, etc.; the UpPTS is anuplink special timeslot succeeding the GP and preceding the timeslot TS1to enable an uplink random access, etc; and the GP is used to preventinterference between uplink and downlink timeslots, i.e., interferenceof the downlink special timeslot with the uplink timeslot. An example ofshortening the data timeslot and the uplink special timeslot isdescribed below.

As illustrated in FIG. 2, the data timeslot and/or the timeslot UpPTSare/is shorten in length, for example, by shortening the data timeslots0# to #6 from 675 μs to 667 μs and the timeslot UpPTS from 141.28 μs to116.67 μs in length to thereby spare 80.61 μs. For the sake ofdescription, a spared timeslot due to shortening the data timeslot isreferred to as a first timeslot, and a spared timeslot due to shorteningthe timeslot UpPTS is referred to as a second timeslot. The shorteningmay be implemented by reducing the length of the CP in the data timeslotand/or of the CP in the timeslot UpPTS, for example, by changing thelength of a long CP from 544×Ts to 512×Ts and a short CP from 256×Ts to224×Ts; alternatively, the shortening may be implemented by reducingdirectly the number of OFDM symbols in a data timeslot, e.g. the datatimeslot #6. Through the foregoing adjusting of the data frame and thesubsequently reasonable use of the first timeslot and/or the secondtimeslot, it is possible to reduce the interference of the DwPTS withthe uplink timeslot when the DwPTS is drifting to thereby obtain animproved communication quality. Different technical solutions aredescribed below dependent upon locations of the first timeslot.

In a first solution as illustrated in FIG. 3, when the first timeslotand/or the second timeslot compose(s) in length at least one OFDMsymbol, e.g., one OFDM symbol, the first timeslot and/or the secondtimeslot may be arranged at front of the DwPTS, and the S-SCH in theoriginal data timeslot #0 may be arranged in the first timeslot and/orthe second timeslot, so that the S-SCH may be merged together with theP-SCH in the DwPTS to result in a new timeslot DwPTS, and thus onesymbol may be spared in the timeslot #0 to facilitate transmission ofother information to thereby improve a utilization ratio of resources.In this case, the DwPTS may be flexibly positioned due to two OFDMsymbols (i.e. the S-SCH and the P-SCH) contained therein. As illustratedin FIG. 2, the DwPTS is arranged at the head of the data frame and thusmay be spaced away from the UpPTS, to thereby reduce the interference ofthe DwPTS with the uplink timeslot due to a drift or power increase ofthe DwPTS, and hence improve the communication quality. Moreover, sincea signal of the P-SCH is required for the S-SCH to perform channelestimation, the channel estimation may be performed accurately withoutdegrading the performance of the system because both of the P-SCH andthe S-SCH are transmitted in the adjacent symbols.

In a second solution, a part of or all of the first timeslot and/or thesecond timeslot is arranged at the tail of the DwPTS, such that theDwPTS may be further spaced from the UpPTS by an increased distance dueto addition of the succeeding first timeslot, to thereby reduce theinterference of the DwPTS with the uplink timeslot due to a drift orpower increase of the DwPTS and hence improve the communication quality.

In a third solution as illustrated in FIG. 4, a part of or all of thefirst timeslot and/or the second timeslot is arranged in the GP, suchthat the DwPTS may be spaced from the UpPTS by an increased interval dueto an increase in the length of the GP (that is, the length of the GP ismade larger than 50 μs) and hence an extended period of the guardtimeslot, to thereby reduce the interference of the DwPTS with theuplink timeslot due to a drift or power increase of the DwPTS and henceimprove the communication quality.

A Second Embodiment

The present embodiment discloses a communication device including: atransmission unit configured to transmit a radio frame, where eachhalf-frame of the radio frame includes a data timeslot for transmittingdata, and a downlink special timeslot for carrying synchronizationinformation, the data timeslot is shorter than an original datatimeslot, for example, the data timeslots #0 to #6 may be shortened from675 μs to 667 μs as in the foregoing embodiment of the method, and forthe sake of description, a spared timeslot due to shortening the datatimeslot is referred to as a first timeslot, at least a part of which isarranged at the head and/or tail of the downlink special timeslot. Sincethe downlink special timeslot is longer than an original downlinkspecial timeslot, for example, by one OFDM symbol, the S-SCH may bearranged in the OFDM symbol, and in this case one symbol may be sparedin the data timeslot #0 for transmission of other data to therebyimprove the communication efficiency. On the other hand, the downlinkspecial timeslot may be moved as a complete timeslot, for example, tothe head of the half-frame so as to be spaced from an uplink timeslot byan increased distance to thereby reduce the interference of the DwPTSwith the uplink timeslot due to a drift or power increase of the DwPTS.

The present embodiment further discloses another communication deviceincluding a transmission unit configured to transmit a radio frame,where each half-frame of the radio frame includes a data timeslot fortransmitting data, a downlink special timeslot for carryingsynchronization information, and a guard timeslot for preventinginterference between uplink and downlink timeslots, and the datatimeslot is shorter than an originally configured data timeslot by afirst timeslot, at least a part of the first timeslot is located in theguard timeslot, the guard timeslot is longer than an originallyconfigured guard timeslot, and a total length of the data timeslot, thedownlink timeslot and the guard timeslot is kept unchanged. Interferenceof the DwPTS with the uplink timeslot due to a drift or power increaseof the DwPTS may be reduced due to the longer guard timeslot thanoriginally configured and hence an increased distance between thedownlink timeslot and the uplink timeslot.

According to the embodiments of the invention, through shortening thelength of the data timeslot and/or the length of the uplink specialtimeslot and making reasonable use of a spared timeslot part obtained bythe shortening of the data timeslot and/or the uplink special timeslot,for example, by arranging such spared part in the GP, it is possible toincrease an interval between the DwPTS and the UpPTS to thereby reducethe interference of the DwPTS with the uplink timeslot. Alternatively,by composing that spared timeslot part(s) due to the shortening of thedata timeslot and/or the uplink special timeslot into a symbol (referredto as a first symbol for the sake of description) so as to add thatsymbol into the half-frame, it is possible to prevent a symbol of anydata timeslot from being occupied by the S-SCH, so that on one hand autilization ratio of resources may be improved, and on the other handthe timeslot of DwPTS may be moved, for example, by arranging the DwPTSat the head of the half-frame, because two OFDM symbols are contained inthe DwPTS to carry the S-SCH and the P-SCH, to thereby addresseffectively the problem of the interference of the DwPTS with the uplinktimeslot due to an power increase of the DwPTS.

Although the invention has been described in connection with theembodiments thereof, those ordinarily skilled in the art shallappreciate that numerous modifications and variations may be made to theinvention without departing from the scope of the invention as definedin the appended claims.

1. A communication method applicable in a mobile communication system ofLong Term Evolution Type 2 wideband Time Division Duplex, comprising:transmitting, by a first communication device, to a second communicationdevice a radio frame, with each half-frame of the radio frame comprisinga data timeslot for transmitting data, an uplink special timeslot and adownlink special timeslot for carrying synchronization information,wherein the data timeslot is shorter than an original data timeslot by afirst timeslot and/or the uplink special timeslot is shorter than anoriginal uplink special timeslot by a second timeslot; and a part of thefirst timeslot or the second timeslot or the combination of the firsttimeslot and the second timeslot, having the length of one orthogonalfrequency division multiplex symbol, carries a secondary synchronouschannel.
 2. The method according to claim 1, wherein the part carryingthe secondary synchronous channel is included in the downlink specialtimeslot, at least part of the first timeslot and is located at thefront and/or tail of the downlink special timeslot.
 3. The methodaccording to claim 1, wherein a cyclic prefix in the original datatimeslot is shortened so that the data timeslot with the shortenedcyclic prefix is shorter than the original data timeslot by the firsttimeslot; and/or a cyclic prefix in the original uplink special timeslotis shortened so that the uplink special timeslot with the shortenedcyclic prefix is shorter than the original uplink special timeslot bythe second timeslot.
 4. The method according to claim 1, wherein atleast part of the second timeslot is located at the head and/or tail ofthe downlink special timeslot an orthogonal frequency division multiplexsymbol in the original data timeslot is shortened so that the datatimeslot with the shortened orthogonal frequency division multiplexsymbol is shorter than the original data timeslot by the first timeslot.5. The method according to claim 1, wherein the half-frame of the radioframe further comprises a guard timeslot for preventing interferencebetween uplink and downlink timeslots; and at least part of the firsttimeslot and/or at least part of the second timeslot is located in theguard timeslot.
 6. The method according to claim 1, wherein thehalf-frame of the radio frame further comprises an uplink specialtimeslot shorter than an original uplink special timeslot by a secondtimeslot shortened data timeslot is no longer than 667 μs; and/or theshortened uplink special timeslot is no longer than 116.67 μs.
 7. Themethod according to claim 6, wherein at least part of the secondtimeslot is located in the guard timeslot the guard timeslot is longerthan 50 μs.
 8. A communication device applicable in a mobilecommunication system of Long Term Evolution Type 2 wideband TimeDivision Duplex, comprising: a transmission unit configured to transmita radio frame, each half-frame of the radio frame comprising a datatimeslot for transmitting data, an uplink special timeslot and adownlink special timeslot for carrying synchronization information,wherein the data timeslot is shorter than an original data timeslot by afirst timeslot and/or the uplink special timeslot is shorter than anoriginal uplink special timeslot by a second timeslot; and a part of thefirst timeslot or the second timeslot or the combination of the firsttimeslot and the second timeslot, having the length of one orthogonalfrequency division multiplex symbol, carries a secondary synchronouschannel.
 9. The device according to claim 8, wherein at least part ofthe first timeslot is located at the head and/or tail of the downlinkspecial timeslot the part carrying the secondary synchronous channel isincluded in the downlink special timeslot, and is located at the head ofthe downlink special timeslot.
 10. The device according to claim 8,wherein the half-frame the radio frame transmitted from the transmissionunit further comprises a guard timeslot for preventing interferencebetween uplink and downlink timeslots; and at least part of the firsttimeslot and/or at least part of the second timeslot is located in theguard timeslot.
 11. The method according to claim 2, wherein thedownlink special timeslot is arranged at the head of the half-frame. 12.The method according to claim 1, wherein at least part of the firsttimeslot and/or at least part of the second timeslot is located at thetail of the downlink special timeslot.
 13. The device according to claim9, wherein the downlink special timeslot is arranged at the head of thehalf-frame.
 14. The device according to claim 7, wherein at least partof the first timeslot and/or at least part of the second timeslot islocated at the tail of the downlink special timeslot.